Fix crash when importing model with materials and Split Objects enabled

Source/Editor/GUI/ComboBox.cs

@@ -545,7 +545,7 @@ namespace FlaxEditor.GUI
             Render2D.DrawRectangle(clientRect.MakeExpanded(-2.0f), borderColor);
 
             // Check if has selected item
-            if (_selectedIndices.Count > 0)
+            if (_selectedIndices != null && _selectedIndices.Count > 0)
             {
                 string text = _selectedIndices.Count == 1 ? _items[_selectedIndices[0]] : "Multiple Values";
 

Source/Engine/Tools/ModelTool/ModelTool.Assimp.cpp

@@ -716,13 +716,13 @@ bool ModelTool::ImportDataAssimp(const char* path, ImportedModelData& data, Opti
     if (EnumHasAnyFlags(data.Types, ImportDataTypes::Geometry) && context->Scene->HasMeshes())
     {
         const int meshCount = context->Scene->mNumMeshes;
-        if (options.SplitObjects && options.ObjectIndex == -1)
+        if (options.SplitObjects && options.ObjectIndex == -1 && meshCount > 1)
         {
             // Import the first object within this call
             options.SplitObjects = false;
             options.ObjectIndex = 0;
 
-            if (meshCount > 1 && options.OnSplitImport.IsBinded())
+            if (options.OnSplitImport.IsBinded())
             {
                 // Split all animations into separate assets
                 LOG(Info, "Splitting imported {0} meshes", meshCount);
@@ -789,13 +789,13 @@ bool ModelTool::ImportDataAssimp(const char* path, ImportedModelData& data, Opti
     if (EnumHasAnyFlags(data.Types, ImportDataTypes::Animations) && context->Scene->HasAnimations())
     {
         const int32 animCount = (int32)context->Scene->mNumAnimations;
-        if (options.SplitObjects && options.ObjectIndex == -1)
+        if (options.SplitObjects && options.ObjectIndex == -1 && animCount > 1)
         {
             // Import the first object within this call
             options.SplitObjects = false;
             options.ObjectIndex = 0;
 
-            if (animCount > 1 && options.OnSplitImport.IsBinded())
+            if (options.OnSplitImport.IsBinded())
             {
                 // Split all animations into separate assets
                 LOG(Info, "Splitting imported {0} animations", animCount);

Source/Engine/Tools/ModelTool/ModelTool.OpenFBX.cpp

@@ -1245,13 +1245,13 @@ bool ModelTool::ImportDataOpenFBX(const char* path, ImportedModelData& data, Opt
     if (EnumHasAnyFlags(data.Types, ImportDataTypes::Geometry) && context->Scene->getMeshCount() > 0)
     {
         const int meshCount = context->Scene->getMeshCount();
-        if (options.SplitObjects && options.ObjectIndex == -1)
+        if (options.SplitObjects && options.ObjectIndex == -1 && meshCount > 1)
         {
             // Import the first object within this call
             options.SplitObjects = false;
             options.ObjectIndex = 0;
 
-            if (meshCount > 1 && options.OnSplitImport.IsBinded())
+            if (options.OnSplitImport.IsBinded())
             {
                 // Split all animations into separate assets
                 LOG(Info, "Splitting imported {0} meshes", meshCount);
@@ -1328,13 +1328,13 @@ bool ModelTool::ImportDataOpenFBX(const char* path, ImportedModelData& data, Opt
     if (EnumHasAnyFlags(data.Types, ImportDataTypes::Animations))
     {
         const int animCount = context->Scene->getAnimationStackCount();
-        if (options.SplitObjects && options.ObjectIndex == -1)
+        if (options.SplitObjects && options.ObjectIndex == -1 && animCount > 1)
         {
             // Import the first object within this call
             options.SplitObjects = false;
             options.ObjectIndex = 0;
 
-            if (animCount > 1 && options.OnSplitImport.IsBinded())
+            if (options.OnSplitImport.IsBinded())
             {
                 // Split all animations into separate assets
                 LOG(Info, "Splitting imported {0} animations", animCount);

Source/Engine/Tools/ModelTool/ModelTool.cpp

@@ -16,6 +16,7 @@
 #include "Engine/Graphics/Textures/TextureData.h"
 #include "Engine/Graphics/Models/ModelData.h"
 #include "Engine/Content/Assets/Model.h"
+#include "Engine/Content/Content.h"
 #include "Engine/Serialization/MemoryWriteStream.h"
 #if USE_EDITOR
 #include "Engine/Core/Types/DateTime.h"
@@ -909,6 +910,10 @@ bool ModelTool::ImportModel(const String& path, ModelData& meshData, Options& op
     {
         auto& texture = data.Textures[i];
 
+        // When splitting imported meshes allow only the first mesh to import assets (mesh[0] is imported after all following ones so import assets during mesh[1])
+        if (!options.SplitObjects && options.ObjectIndex != 1 && options.ObjectIndex != -1)
+            continue;
+
         // Auto-import textures
         if (autoImportOutput.IsEmpty() || (data.Types & ImportDataTypes::Textures) == ImportDataTypes::None || texture.FilePath.IsEmpty())
             continue;
@@ -994,6 +999,17 @@ bool ModelTool::ImportModel(const String& path, ModelData& meshData, Options& op
             materialOptions.Info.CullMode = CullMode::TwoSided;
         if (!Math::IsOne(material.Opacity.Value) || material.Opacity.TextureIndex != -1)
             materialOptions.Info.BlendMode = MaterialBlendMode::Transparent;
+
+        // When splitting imported meshes allow only the first mesh to import assets (mesh[0] is imported after all following ones so import assets during mesh[1])
+        if (!options.SplitObjects && options.ObjectIndex != 1 && options.ObjectIndex != -1)
+        {
+            // Find that asset create previously
+            AssetInfo info;
+            if (Content::GetAssetInfo(assetPath, info))
+                material.AssetID = info.ID;
+            continue;
+        }
+
         AssetsImportingManager::Create(AssetsImportingManager::CreateMaterialTag, assetPath, material.AssetID, &materialOptions);
 #endif
     }